Communicating THC levels and 'dose' to consumers: Implications for product labelling and packaging of cannabis products in regulated markets.

In a well-regulated drug market, consumers should be able to understand and titrate their dose with little difficulty. In the cannabis market, despite substantial increases in THC levels over time, users have had limited information on the strength of their products. In principle, cannabis legalization provides greater opportunity to communicate clear, accurate information to consumers through packaging and labelling standards. However, jurisdictions that have legalized cannabis have experienced an increase in adverse events from higher strength products, particularly from edibles and other concentrates. What little research exists suggests that current regulatory practices of labelling THC levels on packages may be ineffective due to consumer difficulties understanding numbers (e.g., mg vs. percentage), and the different ways THC levels are communicated across product categories. In particular, current labelling practices provide little guidance in terms of 'dose expression'-how THC 'dose' translates into consumption amounts for specific products. The current paper identifies five principles to guide cannabis labelling and packaging regulations, including considerations for numeric THC labelling, the use of standard servings or dose across different product forms, strategies to communicate 'dose expression', and 'dose-unit packaging'. Overall, there is a need for regulated cannabis markets to develop more effective packaging and labelling standards to allow consumers to effectively titrate their THC intake, with the goal of promoting lower-risk cannabis use.